.Net模擬提交表單

2016-09-0210:49:20

　　以中郵速遞API爲服務接口，因爲提交方式爲表單提交，我要獲取返回值來處理其餘業務，因此一開始嘗試採用Js後臺獲取返回值，可是涉及到跨域請求限制問題，那邊服務端接口返回的是json而不能處理jsonp；因此開始着手考慮後臺模擬提交表單；

　　網上開始查資料，對於後臺提交表單的一些相關資料：

• 表單提交協議規定：

　　 對於含文件的表單提交，要先將 HTTP 要求的 Content-Type 設爲 multipart/form-data，並且要設定一個 boundary 參數，
　　這個參數是由應用程序自行產生，它會用來識別每一份資料的邊界 (boundary)，用以產生多重信息部份 (message part)。

• 基本內容：

　　1. 每一個信息部份都要用 --[BOUNDARY_NAME] 來包裝，以分隔出信息的每一個部份，而最後要再加上一個 --[BOUNDARY_NAME] 來表示結束。　　
　　2. 每一個信息部份都要有一個 Content-Disposition: form-data; name=""，而 name 設定的就是 HTTP POST 的鍵值 (key)。
　　3. 聲明區和值區中間要隔兩個新行符號（\r\n）。
　　4. 中間能夠夾入二進制資料，但二進制資料必需要格式化爲二進制字符串。
　　5. 若要設定不一樣信息段的資料型別 (Content-Type)，則要在信息段內的聲明區設定。

• 內容模板：

　　兩個form內容模板
　　boundary = "----" + DateTime.Now.Ticks.ToString("x");//程序生成
　　1.文本內容
　　"\r\n--" + boundary +
　　"\r\nContent-Disposition: form-data; name=\"鍵\"; filename=\"文件名\"" +
　　"\r\nContent-Type: application/octet-stream" +
　　"\r\n\r\n";
　　2.文件內容
　　"\r\n--" + boundary +
　　"\r\nContent-Disposition: form-data; name=\"鍵\"" +

　　　"\r\n\r\n內容";

•  單個文件或文本的實體類：

/// <summary>
    /// 單個文件或鍵值
    /// </summary>
    public class FormItemModel
    {
        /// <summary>  
        /// 表單鍵，request["key"]  
        /// </summary>  
        public string Key { set; get; }
        /// <summary>  
        /// 表單值,上傳文件時忽略，request["key"].value  
        /// </summary>  
        public string Value { set; get; }
        /// <summary>  
        /// 是不是文件  
        /// </summary>  
        public bool IsFile
        {
            get
            {
                if (FileContent == null || FileContent.Length == 0)
                    return false;

                if (FileContent != null && FileContent.Length > 0 && string.IsNullOrWhiteSpace(FileName))
                    throw new Exception("上傳文件時 FileName 屬性值不能爲空");
                return true;
            }
        }
        /// <summary>  
        /// 上傳的文件名  
        /// </summary>  
        public string FileName { set; get; }
        /// <summary>  
        /// 上傳的文件內容  
        /// </summary>  
        public Stream FileContent { set; get; }
    }

提交表單主邏輯實現：

  /// <summary>  
        /// 使用Post方法獲取字符串結果  
        /// </summary>  
        /// <param name="url"></param>  
        /// <param name="formItems">Post表單內容</param>  
        /// <param name="cookieContainer"></param>  
        /// <param name="timeOut">默認20秒</param>  
        /// <param name="encoding">響應內容的編碼類型（默認utf-8）</param>  
        /// <returns></returns>  
        public static string FormSubmit(string url, List<FormItemModel> formItems, CookieContainer cookieContainer = null, string refererUrl = null, Encoding encoding = null, int timeOut = 20000)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            #region 初始化請求對象
            request.Method = "POST";
            request.Timeout = timeOut;
            request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";
            request.KeepAlive = true;
            request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36";
            if (!string.IsNullOrEmpty(refererUrl))
                request.Referer = refererUrl;
            if (cookieContainer != null)
                request.CookieContainer = cookieContainer;
            #endregion

            string boundary = "----" + DateTime.Now.Ticks.ToString("x");//分隔符  
            request.ContentType = string.Format("multipart/form-data; boundary={0}", boundary);
            //請求流  
            var postStream = new MemoryStream();
            #region 處理Form表單請求內容
            //是否用Form上傳文件  
            var formUploadFile = formItems != null && formItems.Count > 0;
            if (formUploadFile)
            {
                //文件數據模板  
                string fileFormdataTemplate =
                    "\r\n--" + boundary +
                    "\r\nContent-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"" +
                    "\r\nContent-Type: application/octet-stream" +
                    "\r\n\r\n";
                //文本數據模板  
                string dataFormdataTemplate =
                    "\r\n--" + boundary +
                    "\r\nContent-Disposition: form-data; name=\"{0}\"" +
                    "\r\n\r\n{1}";
                foreach (var item in formItems)
                {
                    string formdata = null;
                    if (item.IsFile)
                    {
                        //上傳文件  
                        formdata = string.Format(
                            fileFormdataTemplate,
                            item.Key, //表單鍵  
                            item.FileName);
                    }
                    else
                    {
                        //上傳文本  
                        formdata = string.Format(
                            dataFormdataTemplate,
                            item.Key,
                            item.Value);
                    }
                    //統一處理  
                    byte[] formdataBytes = null;
                    //第一行不須要換行  
                    if (postStream.Length == 0)
                        formdataBytes = Encoding.UTF8.GetBytes(formdata.Substring(2, formdata.Length - 2));
                    else
                        formdataBytes = Encoding.UTF8.GetBytes(formdata);
                    postStream.Write(formdataBytes, 0, formdataBytes.Length);

                    //寫入文件內容  
                    if (item.FileContent != null && item.FileContent.Length > 0)
                    {
                        using (var stream = item.FileContent)
                        {
                            byte[] buffer = new byte[1024];
                            int bytesRead = 0;
                            while ((bytesRead = stream.Read(buffer, 0, buffer.Length)) != 0)
                            {
                                postStream.Write(buffer, 0, bytesRead);
                            }
                        }
                    }
                }
                //結尾  
                var footer = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");
                postStream.Write(footer, 0, footer.Length);
            }
            else
            {
                request.ContentType = "application/x-www-form-urlencoded";
            }
            #endregion

            request.ContentLength = postStream.Length;

            #region 輸入二進制流
            if (postStream != null)
            {
                postStream.Position = 0;
                //直接寫入流  
                Stream requestStream = request.GetRequestStream();

                byte[] buffer = new byte[1024];
                int bytesRead = 0;
                while ((bytesRead = postStream.Read(buffer, 0, buffer.Length)) != 0)
                {
                    requestStream.Write(buffer, 0, bytesRead);
                }
                postStream.Close();//關閉文件訪問  
            }
            #endregion

            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            if (cookieContainer != null)
            {
                response.Cookies = cookieContainer.GetCookies(response.ResponseUri);
            }

            using (Stream responseStream = response.GetResponseStream())
            {
                using (StreamReader myStreamReader = new StreamReader(responseStream, encoding ?? Encoding.UTF8))
                {
                    string retString = myStreamReader.ReadToEnd();
                    return retString;
                }
            }
        }

public static Stream FileToStream(string fileName)
{
// 打開文件
FileStream fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
// 讀取文件的 byte[]
byte[] bytes = new byte[fileStream.Length];
fileStream.Read(bytes, 0, bytes.Length);
fileStream.Close();
// 把 byte[] 轉換成 Stream
Stream stream = new MemoryStream(bytes);
return stream;
}

• 調用實例，請求中郵速遞API

   public static string FormSubmitDemo()
          {
              //中郵速遞API
              var url = "http://captureupload.30post.cn/capture/index/idcard_upload";
              var log1 = @"C:\Users\fmh\Desktop\圖片\1.jpg";
              var log2 = @"C:\Users\fmh\Desktop\圖片\2.jpg";
              var formDatas = new List<FormItemModel>();
              //添加文件  
              formDatas.Add(new FormItemModel()
              {
                  Key = "card_photo",
                  Value = "",
                  FileName = "1.jpg",
                  FileContent = FileToStream(log1)
              });
              formDatas.Add(new FormItemModel()
              {
                  Key = "card_photob",
                  Value = "",
                  FileName = "2.jpg",
                  FileContent = FileToStream(log2)
              });
              //添加文本  
              formDatas.Add(new FormItemModel()
              {
                  Key = "name",
                  Value = "測試"
              });
              formDatas.Add(new FormItemModel()
              {
                  Key = "id_card",
                  Value = "371916199103191319"
              });
              formDatas.Add(new FormItemModel()
              {
                  Key = "mobile",
                  Value = "18722354113"
              });
              formDatas.Add(new FormItemModel()
              {
                  Key = "order_no",
                  Value = "371916199103191319"
              });
              //提交表單  
              var result = FormSubmit(url, formDatas);
              return result;
          }